Allows usage in challenging light level situations due to increased photon detection probability for incident light
Introducing the latest avalanche photodiode (APD) and single-photon avalanche diode (SPAD) devices, X-FAB Silicon Foundries has proven automotive-qualified 180 nm XH018 high-voltage process by enhancing APDs and SPADs with several architectural modifications.
This allows usage in situations where there are light level challenges involved. At the same time, footprint compatibility with the previous generation has been retained. This means that a simple and convenient upgrade path is assured, with no additional engineering work.
One of the most noticeable areas with respect to a performance boost is in the photon detection probability (PDP), having a 42% PDP figure for incident light at 405 nm, while the improvement in the near-infrared (NIR) frequencies is as much as 150%, with a 5% PDP being demonstrated at 850 nm. An afterpulsing probability of 0.9% represents a 70% reduction compared to the first-generation devices. The dark count rate (DCR) is only 13 counts/s/µm² and the fill factor (the percentage of these sensors’ surface area that is active) has almost doubled to 33%.
As breakdown voltage characteristics can vary from device to device, an exact determination is necessary to ensure good APD/SPAD performance. For this reason, a trigger diode has been incorporated, which allows precise, real-time on-chip breakdown voltage detection without an external light source. Active quenching circuitry is included for accelerating the rate at which the SPAD devices recover and are ready for further light detection. The new SPADs offer better application adaptation due to their size flexibility (in terms of both width and length). First-time-right design is supported by complete device models for the SPAD and APD devices.
“Thanks to the combination of elevated PDP and competitive DCR levels, we are presenting the market with APD/SPAD solutions that have impressive signal integrity characteristics, which will directly benefit our customers for applications like computer tomography and fluorescence detection within the medical sector, as well for time-of-flight and LiDAR in industrial and automotive systems,” states Detlef Sommer, Business Line Manager for Opto Technologies at X-FAB. “These advanced optoelectronic elements are valuable additions to the X-FAB design kit, broadening the selection of interoperable assets based on the XH018 process that can be made use of.”
